#include<iostream>
#include<fstream>

ifstream in("fact.in");
ofstream out("fact.out");

int main()
{
 int p,ok=0,n,twos=0,fives=0,pp;
 in>>p;

 for(n=1;ok==0 && n>0;n++)
 {
  pp=n;
  while(pp%5==0){
   if (pp%5==0) { fives++; pp=pp/5;}
   }

  if(fives>=p)
   ok=n;
 }

 if(fives != p) out<<-1;
 else out<<ok;

 out.close();
 in.close();

 return 0;
}